Image pickup device including photodetection surface and transfer control arrangement

ABSTRACT

A fluorescence correlation spectroscopy analyzer  1  is equipped with an excitation light illuminating optical system  21 , a fluorescence imaging optical system  22 , a CCD camera  15 , and a data analyzer  16 . The excitation light illuminating optical system  21  illuminates excitation light onto a predetermined region of a measured sample S. The fluorescence imaging optical system  22  images the fluorescence generated at the measured sample S onto the photodetection surface of the CCD camera  15 . The CCD camera  15  performs photoelectric conversion of the fluorescence made incident onto the photodetection surface in accordance with the respective pixels and outputs the charges generated by the photoelectric conversion as detection signals from an output terminal. The data analyzer  16  inputs the detection signals based on the charges generated at the pixels, and computes autocorrelation functions of the input detection signals according to each pixel.

This is a continuation application of application Ser. No. 10/545,393,having a §371 date of May 23, 2006 now U.S. Pat. No. 7,400,396, which isa national stage filing based on PCT International Application No.PCT/JP2004/001558, filed on Feb. 13, 2004. The application Ser. No.10/545,393 is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a fluorescence correlation spectroscopyanalyzer.

BACKGROUND ART

Fluorescence correlation spectroscopy (FCS) is a method wherein thefluorescence fluctuations (variations of the fluorescence intensity intime) of fluorescent molecules in a measured sample are measured andautocorrelation functions are determined from the fluorescencefluctuations to analyze the translational diffusion motions, etc., ofthe fluorescent molecules. By FCS, for example, the binding and motionof a single protein molecule can be analyzed.

Examples of conventional analyzers that make use of FCS include thosedescribed in Document 1 (Japanese Patent Application Laid-Open No.2000-166598), Document 2 (Japanese Patent Application Laid-Open No.2001-272346), and Document 3 (Japanese Patent Application Laid-Open No.2001-194305). With the analyzer described in Document 1, a point-likeexcitation light is illuminated onto a single point of a measured sampleand the fluorescence emitted from the measured sample is detected by adetector, such as a photomultiplier tube (PMI) or an avalanchephotodiode (APD). With the analyzer described in Document 2, pulseexcitation light is illuminated onto a measured sample while scanningand the fluorescence from the measured sample is detected by a CCDcamera.

DISCLOSURE OF THE INVENTION

With the analyzer described in Document 1, since the excitation light isilluminated onto just one point of the measured sample, a plurality ofpoints of the measured sample cannot be analyzed simultaneously Movementof a substance within a cell thus cannot be measured.

On the other hand, with the analyzer described in Document 2, by the useof the CCD camera as the detector, simultaneous analysis of a pluralityof points of a measured sample is enabled. However, when a CCD camera isused, since the detection signals of the respective pixels must be readout in order one by one, a large amount of time is required to read outthe detection signals of a single frame. Thus, with the analyzerdescribed in Document 2, detection signals cannot be read out at a highspeed, for example, in the order of μs. Thus, an analyzer, capable ofperforming fluorescence correlation spectroscopy analysis of fluorescentmolecules at multiple points within a micro-time domain of the μs level,etc., did not exist.

The present invention has been made to resolve the above issues and anobject thereof is to provide a fluorescence correlation spectroscopyanalyzer that enables fluorescence correlation spectroscopy analysis tobe performed simultaneously on multiple points of a measured sample athigh speed.

In order to resolve the above issues, the present invention'sfluorescence correlation spectroscopy analyzer comprises: an excitationlight illuminating optical system, illuminating excitation light onto apredetermined region of a measured sample; a fluorescence imagingoptical system, imaging the fluorescence emitted from fluorescentmolecules within the predetermined region of the measured sample ontowhich the excitation light has been illuminated from the excitationlight illuminating optical system; a detector, having a photodetectionsurface, disposed on an image plane position of the fluorescence imagedby the fluorescence imaging optical system and provided with a pluralityof pixels that are arrayed two-dimensionally along a first direction anda second direction that intersect mutually, photoelectricallyconverting, according to the respective pixels, the fluorescence madeincident on the photodetection surface, transferring the chargesgenerated by the photoelectrical conversion in the first direction andthe second direction, and outputting the charges as detection signalsfrom an output terminal; and an analyzing unit, inputting the detectionsignals from pixels belonging to a pixel set, comprising a portion ofpixels selected from among all of the pixels, arrayed on thephotodetection surface, in accordance with the incidence region of thephotodetection surface on which the fluorescence is imaged by thefluorescence imaging optical system, and determining an autocorrelationfunction for each of the detection signals.

With this fluorescence correlation spectroscopy analyzer, excitationlight is illuminated onto the predetermined region of the measuredsample by the excitation light illuminating optical system. Thefluorescence emitted from the fluorescent molecules in the predeterminedregion of the measured sample onto which the excitation light has beenilluminated is then imaged on the photodetection surface of the detectorby the fluorescence imaging optical system. The fluorescence madeincident on the photodetection surface is then photoelectricallyconverted according to the respective pixels. The charges generated atthe respective pixels by the photoelectric conversion are output asdetection signals from the output terminal of the detector. Thedetection signals output from the detector are input into the analyzingunit. At the analyzing unit, the autocorrelation functions of thedetection signals are determined.

Thus, with this fluorescence correlation spectroscopy analyzer, thefluorescence, emitted from multiple points within the region of themeasured sample onto which the excitation light has been illuminated, isdetected by the plurality of pixels of the detector that correspond tothese points to enable fluorescence correlation spectroscopy analysis ofthe multiple points of the measured sample to be performedsimultaneously. Also, by the use of a charge transfer typetwo-dimensional photodetector as the detector, the fluorescencegenerated at multiple points of the measured sample can be detected by asimple device arrangement.

Furthermore, the analyzing unit determines the autocorrelation functionsof the detection signals based on the charges generated at the pixelsbelonging to the pixel set that is comprised of a portion of the pixelsof the entirety of pixels arrayed on the photodetection surface. Thus,with the detector, the charges generated at all of the pixels of thephotodetection surface do not need to be output as effective detectionsignals, and it is sufficient that at least the pixels belonging to thepixel set be output as the detection signals. Thus, with thisfluorescence correlation spectroscopy analyzer, the time required foroutputting the charges of a single frame from the detector can beshortened. Fluorescence correlation spectroscopy analysis can thus beperformed at high speed on multiple points of a measured sample withthis fluorescence correlation spectroscopy analyzer.

Preferably on the photodetection surface, the pixels in the fluorescenceincidence region substantially match the pixels belonging to the pixelset. In this case, at the analyzing unit, the autocorrelation functionsare determined for the detection signals based on the charges generatedat the pixels onto which the fluorescence, generated at thepredetermined region of the measured sample illuminated by theexcitation light, is made incident. Both the fluorescence made incidenton the photodetection surface of the detector and the excitation lightilluminated onto the measured sample are thereby used effectively influorescence correlation spectroscopy analysis.

Preferably, a scanning means is equipped by which the excitation light,illuminated by the excitation light illuminating optical system onto thepredetermined region of the measured sample, is scanned with respect tothe measured sample. In this case, fluorescence correlation spectroscopyanalysis can be performed on a wide range of the measured sample.

Preferably, the scanning means is a galvanomirror. In this case, theexcitation light can be scanned with respect to the measured sample atan especially high precision.

Preferably, the detector has a horizontal transfer register, whichreceives and accumulates the charges that are transferred in the firstdirection from the pixels and transfers the accumulated charges in thesecond direction, and a transfer control means, which outputs, to therespective pixels and the horizontal transfer register, transfer signalsfor transferring charges, and the transfer control means outputs thetransfer signals so that the charges generated at the pixels notbelonging to the pixel set are overlapped in the first direction andaccumulated in the horizontal transfer register and thereaftertransferred in the second direction while the charges generated at thepixels belonging to the pixel set are accumulated in the first directionand transferred in the second direction one stage at a time.

In this case, since the transfer control means makes the charges,resulting from photoelectric conversion by the pixels not belonging tothe pixel set, be accumulated in an overlapping manner, the charges thatare not used as effective data can be collected together. That is, sincethe charges, generated by photoelectric conversion at the pixels, whichdo not belong to the pixel set but are positioned across a plurality ofstages, can be swept out in a single transfer in the second direction,the charges generated by photoelectric conversion at the pixelsbelonging to the pixel set can be read out at a higher speed.

Preferably, the transfer control means outputs the transfer signals tothe pixels belonging to the pixel set to make the charges generated atthe pixels belonging to the pixel set be transferred in the firstdirection, and in the case where one stage of pixels aligned in thesecond direction includes pixels belonging to the pixel set, outputs thetransfer signal to the horizontal transfer register at the stage priorto the transfer of the charges generated at the one stage of pixels tothe horizontal transfer register.

In this case, since at the stage before the charges, which have beengenerated by photoelectric conversion at the pixels belonging to thepixel set, are transferred successively to the horizontal transferregister, the transfer control means outputs the transfer signal to thehorizontal transfer register, the charges accumulated in the horizontaltransfer register can be swept out efficiently.

Preferably, in the case where one stage of pixels aligned in the seconddirection includes pixels belonging to the pixel set and pixels notbelonging to the pixel set, the transfer control means outputs thetransfer signals to the pixels of the one stage and thereby makes thecharges be transferred to the horizontal transfer register when theelements of the horizontal transfer register, which correspond to thepixels belonging to the pixel set of the one stage, have charges sweptout therefrom and are enabled to receive new charges.

For example, in the case where among the pixels of the one stage, pixelsthat are close to the center are pixels belonging to the pixel set andpixels that are close to the respective ends are pixels not belonging tothe pixel set, the transfer signals are output to the pixels of the onestage when the charges in the stage prior to this one stage have beenswept out successively so that the elements of the horizontal transferregister corresponding to the pixels close to the center of the onestage are enabled to receive new charges. In this case, although thecharges generated by photoelectric conversion at the pixels close to therespective ends are overlapped with the charges at the other stages,since the charges resulting from photoelectric conversion by the pixelsclose to the respective ends are charges that are not used as effectivedetection signals, the actual influence thereof will be extremely small.The charges generated by photoelectric conversion at the pixelsbelonging to the pixel set can thus be read out at a higher speed.

Preferably, the detector has first charge accumulating elements,accumulating charges generated at the respective pixels and transferringthe accumulated charges in the first direction, and second chargeaccumulating elements, receiving and accumulating charges transferred inthe first direction from the first charge accumulating elements andtransferring the accumulated charges in the second direction, thetransfer control means outputs, to the first charge accumulatingelements and the second charge accumulating elements, transfer signalsfor transfer of charges, and in the case where one stage of pixelsaligned in the second direction includes pixels belonging to the pixelset and pixels not belonging to the pixel set, the transfer controlmeans outputs the transfer signals to the first charge accumulatingelements corresponding to the pixels of the one stage and thereby makesthe charges be transferred to the second charge accumulating elementswhen the second charge accumulating elements, which correspond to thepixels belonging to the pixel set of the one stage, have charges sweptout therefrom and are enabled to receive new charges.

In this case, since the transfer control means makes the charges,resulting from photoelectric conversion by the pixels not belonging tothe pixel set, be accumulated in an overlapping manner, the charges thatare not used as effective data can be collected together. Since thecharges, generated by photoelectric conversion at the pixels, which donot belong to the pixel set but are positioned across a plurality ofstages, can be swept out in a single transfer in the second direction,the charges generated by photoelectric conversion at the pixelsbelonging to the pixel set can be read out at a higher speed. Also, forexample, in the case where, among the pixels of the one stage, pixelsthat are close to the center are pixels belonging to the pixel set andpixels that are close to the respective ends are pixels not belonging tothe pixel set, transfer signals are output to the first chargeaccumulating elements corresponding to the pixels of the one stage whenthe charges in the stage prior to this one stage have been swept outsuccessively so that the second charge accumulating elementscorresponding to the pixels close to the center of the one stage areenabled to receive new charges. In this case, although the chargesgenerated by photoelectric conversion at the pixels close to therespective ends are overlapped with the charges at the other stages,since the charges resulting from photoelectric conversion by the pixelsclose to the respective ends are charges that are not used as effectivedetection signals, the actual influence thereof will be extremely small.The charges generated by photoelectric conversion at the pixelsbelonging to the pixel set can thus be read out at a higher speed.

Preferably, the fluorescence correlation spectroscopy analyzer isequipped with an electronic shutter signal outputting means, whichoutputs, to the photodetection surface, an electronic shutter signal forsweeping away the charges generated by the pixels not belonging to thepixel set. In this case, when in reading the charges from the detector,horizontal transfer by the horizontal transfer register or the secondcharge accumulating elements does not need to be executed if the chargesgenerated by the pixels belonging to the pixel set are not accumulatedin the horizontal transfer register or the second charge accumulatingelements. The charges generated by photoelectric conversion at thepixels belonging to the pixel set can thus be read at higher speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an arrangement diagram showing an embodiment of a fluorescencecorrelation spectroscopy analyzer.

FIG. 2 is a plan view showing the CCD camera of FIG. 1 as viewed fromthe photodetection surface side.

FIG. 3 is an arrangement diagram showing an example of an optical systemin the fluorescence correlation spectroscopy analyzer of FIG. 1.

FIGS. 4A to 4D are diagrams for describing the flow of fluorescencecorrelation spectroscopy analysis using the fluorescence correlationspectroscopy analyzer shown in FIG. 1.

FIG. 5 is a diagram for describing an example of the operations ofreading detection signals from the CCD camera in the fluorescencecorrelation spectroscopy analyzer.

FIGS. 6A to 6D are diagrams for describing an example of the operationsof reading detection signals from the CCD camera in the fluorescencecorrelation spectroscopy analyzer.

FIG. 7 shows timing charts that illustrate the operation timing of theCCD camera in the reading operation illustrated in FIG. 5 and FIGS. 6Ato 6D.

FIG. 8 is a graph showing an example of the variation in time of thefluorescence intensity detected by the CCD camera.

FIG. 9 is a graph showing an autocorrelation function G(τ) determinedbased on the graph of FIG. 8.

FIGS. 10A to 10E are diagrams for describing a modification example ofthe fluorescence correlation spectroscopy analyzer of FIG. 1.

FIGS. 11A to 11G are diagrams for describing another modificationexample of the fluorescence correlation spectroscopy analyzer of FIG. 1.

FIGS. 12A to 12G are diagrams for describing another modificationexample of the fluorescence correlation spectroscopy analyzer of FIG. 1.

FIGS. 13A to 13D are diagrams for describing the effects of themodification examples described using FIGS. 10A to 10E, FIGS. 11A to11G, and FIGS. 12A to 12G.

FIGS. 14A and 14B are diagrams for describing the operation timings ofthe respective CCDs during the operations described using FIGS. 10A to10E, FIGS. 11A to 11G, and FIGS. 12A to 12G.

FIGS. 15A and 15B are diagrams for describing the operation timings ofthe respective CCDs during the operations described using FIGS. 10A to10E, FIGS. 11A to 11G, and FIGS. 12A to 12G.

FIGS. 16A to 16L are diagrams for describing another example of theoperations of reading detection signals from the CCD camera in thefluorescence correlation spectroscopy analyzer.

FIGS. 17A to 17K are diagrams for describing another example of theoperations of reading detection signals from the CCD camera in thefluorescence correlation spectroscopy analyzer.

BEST MODES FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention's fluorescencecorrelation spectroscopy analyzer shall now be described in detail alongwith the drawings. In the description of the drawings, the same elementsshall be provided with the same symbols and redundant description shallbe omitted. The dimensional proportions in the drawings do notnecessarily match those of the description.

FIG. 1 is an arrangement diagram showing an embodiment of the presentinvention's fluorescence correlation spectroscopy analyzer. Thefluorescence correlation spectroscopy analyzer 1 illuminates excitationlight onto a measured sample, detects the fluorescence emitted fromfluorescent molecules in the measured sample due to the illumination ofthe excitation light, and determines autocorrelation functions of thefluorescence fluctuations based on the detection signals to analyzetranslational diffusion motions, etc., of the fluorescent molecules. Thefluorescence correlation spectroscopy analyzer 1 is equipped with anexcitation light illuminating optical system 21, a fluorescence imagingoptical system 22, a CCD camera 15 (detector), and a data analyzer 16(analyzing unit).

The excitation light illuminating optical system 21 has a light source,which outputs excitation light, and a light guiding optical system,which guides the excitation light output from the light source, and ispositioned so that its optical axis is directed toward the measuredsample S. The excitation light illuminating optical system 21illuminates the excitation light onto a predetermined region R of themeasured sample S. A region R, onto which this excitation light isilluminated, is selected so as to contain a region of the measuredsample S on which fluorescence correlation spectroscopy analysis isdesired to be carried out.

The fluorescence imaging optical system 22 is positioned with itsoptical axis directed toward the measured sample S and forms an image ofthe fluorescence that is emitted from the fluorescent molecules in theregion of the measured sample S onto which the excitation light has beenilluminated. The fluorescence imaging optical system 22 may bepositioned so that its optical axis is parallel to the optical axis ofthe excitation light illuminating optical system 21 or so that itsoptical axis forms a predetermined angle with the optical axis of theexcitation light illuminating optical system 21.

The CCD camera 15 is connected to the fluorescence imaging opticalsystem 22. The CCD camera 15 has a photodetection surface 32, a transfercontrol unit 152, and an electronic shutter signal outputting unit 154.The CCD camera 15 is positioned so that its photodetection surface 32 isset at the image plane position of the fluorescence that is imaged bythe excitation light illuminating optical system 21. On thephotodetection surface 32, a plurality of pixels P are arrayedtwo-dimensionally along a vertical direction (first direction) and ahorizontal direction (second direction). The CCD camera 15photoelectrically converts, according to the respective pixels P, thefluorescence made incident on photodetection surface 32, guides thecharges, generated by the photoelectric conversion, to an outputterminal by transferring the charges in the vertical direction and thehorizontal direction, and outputs the charges guided to the outputterminal as detection signals from the output terminal.

The region of photodetection surface 32 onto which the fluorescenceimaged by the fluorescence imaging optical system 22 is made incident isindicated by slanted lines in the figure. This region is thefluorescence incidence region 32 a. The set of pixels, comprised ofpixels selected in accordance with the fluorescence incidence region 32a, is the analyzed pixel set 33 a. Here, the analyzed pixel set 33 a isselected so that the region thereof matches the fluorescence incidenceregion 32 a. The analyzed pixel set 33 a is arranged from a plurality ofpixels that occupy a portion of all of the pixels arrayed on thephotodetection surface 32.

The transfer control unit 152 is a transfer control means that outputs,to the respective pixels P of the photodetection surface 32 and to ahorizontal transfer register (not shown), transfer signals fortransferring charges. The electronic shutter signal outputting unit 154is an electronic shutter signal outputting means that outputs anelectronic shutter signal to the photodetection surface 32 for sweepingaway the charges generated by pixels not belonging to the analyzed pixelset 33 a. The provision of the electronic shutter signal outputting unit154 is not essential.

The data analyzer 16 is connected to the CCD camera 15. The dataanalyzer 16 inputs the detection signals that are based on the chargesgenerated by photoelectric conversion at the pixels belonging to theanalyzed pixel set 33 a among pixels P arrayed on the photodetectionsurface 32 of the CCD camera 15 and computes autocorrelation functions,respectively, for the input detection signals. The data analyzer 16analyzes, as necessary, the diffusion motions of the fluorescencemolecules of the measured sample S based on the computed autocorrelationfunctions.

In order to process the detection signals input from the CCD camera 15in a manner associated with pixels P corresponding to the respectivedetection signals, the data analyzer 16 inputs information concerningtransfer control by the transfer control unit 152 of the CCD camera 15.Furthermore, the data analyzer 16 selects the pixels making up theanalyzed pixel set 33 a in accordance with the fluorescence incidenceregion 32 a of the photodetection surface 32. The data analyzer 16provides, to the transfer control unit 152 and the electronic shuttersignal outputting unit 154 of the CCD camera 15, instructions concerningthe respective transfer control and instructions concerning the outputof the electronic shutter signal as necessary. The data analyzer 16comprises, for example, an image acquisition board and a computer.

With the fluorescence correlation spectroscopy analyzer 1 of theabove-described arrangement, excitation light is illuminated onto apredetermined region of the measured sample S by the excitation lightilluminating optical system 21. The fluorescence, emitted from thefluorescent molecules in the region of the measured sample S onto whichthe excitation light has been illuminated, is imaged by the fluorescenceimaging optical system 22 onto the photodetection surface 32 of the CCDcamera 15. The fluorescence that is made incident on the photodetectionsurface 32 is photoelectrically converted according to the respectivepixels. The charges generated at the respective pixels by thephotoelectric conversion are transferred as necessary in the verticaldirection and the horizontal direction and thereafter output asdetection signals from the output terminal of the CCD camera 15. Thedetection signals output by the CCD camera 15 are input into the dataanalyzer 16. At the data analyzer 16, autocorrelation functions of theinput detection signals are determined and the diffusion motions of thefluorescent molecules are analyzed based on the autocorrelationfunctions.

The effects of the fluorescence correlation spectroscopy analyzer 1shall now be described. With the fluorescence correlation spectroscopyanalyzer 1, the fluorescence generated at multiple points inside theregion of the measured sample S onto which the excitation light has beenilluminated is detected by the plurality of pixels of the CCD camera 15that correspond to these points to enable fluorescence correlationspectroscopy analysis to be performed simultaneously on the multiplepoints of the measured sample S. Also, by using the CCD camera 15, whichis a charge transfer type two-dimensional photodetector, thefluorescence generated at the multiple points of the measured sample Scan be detected by a simple device arrangement.

Furthermore, the data analyzer 16 determines the autocorrelationfunctions of the detection signals based on the charges generated at thepixels belonging to the analyzed pixel set 33 a, which is comprised of aportion of the pixels of the entirety of pixels arrayed on thephotodetection surface. Thus, with the CCD camera 15, there is not needto output the charges generated at all pixels of the photodetectionsurface as effective detection signals, and it is sufficient that atleast the charges generated at the pixels belonging to the analyzedpixel set be output as the detection signals. Thus, with thefluorescence correlation spectroscopy analyzer 1, the time required tooutput the charges corresponding to a single frame from the CCD camera15 can be reduced. The fluorescence correlation spectroscopy analysiscan thus be performed at high speed on the multiple points of themeasured sample S by the fluorescence correlation spectroscopy analyzer1.

Also, with the fluorescence correlation spectroscopy analyzer 1, sincethe data analyzer 16 is provided, a measurer can readily know theresults of fluorescence correlation spectroscopy analysis. The resultsof fluorescence correlation spectroscopy analysis include suchinformation as how the fluorescent molecules in the measured sample Sbind or move and how the size and number of the fluorescent moleculeschange accordingly at the respective positions of the measured sample S,for example.

Also, in the case where the pixels in the fluorescence incidence regionof the photodetection surface and the pixels belonging to the analyzedpixel set are substantially matched, the data analyzer 16 determines theautocorrelation functions of the detection signals that are based on thecharges generated at the pixels onto which is made incident thefluorescence generated at the region of the measured sample Silluminated by the excitation light. The fluorescence that is madeincident on the photodetection surface of the CCD camera 15 is thus usedeffectively in fluorescence correlation spectroscopy analysis.

The fluorescence correlation spectroscopy analyzer 1 can be usedfavorably even-under concentration conditions where only one or a fewfluorescent molecules exist at a portion of the measured sample Scorresponding to a single pixel of the photodetection surface of the CCDcamera 15. In this case, if the information on fluorescence intensity isacquired at a high frame rate, the average number of molecules existingat each portion of the measured sample S corresponding to each pixel ofthe analyzed pixel set of the photodetection surface can be made knownby the fluorescence intensity.

With the fluorescence correlation spectroscopy analyzer 1, sincefluorescence correlation spectroscopy analysis of multiple points of themeasured sample S can be performed simultaneously as mentioned above,and since the detection signals from the CCD camera 15 can be read athigh speed, fluorescence correlation spectroscopy analysis can beperformed simultaneously on a certain region of the measured sample S.The movement of substances inside a cell can thus be evaluated andseveral types of samples can be analyzed in vitro simultaneously. Thefluorescence correlation spectroscopy analyzer 1 is thus widelyapplicable to the analysis of protein binding processes, drug screening,etc.

An analyzer that can perform fluorescence correlation spectroscopyanalysis on multiple points of a measured sample is described in theabove-mentioned Document 3 as well. However, the analyzer described inDocument 3 uses a method called scanning FCS, wherein while scanning apoint-like excitation light across a sample, the deflection ofphotoelectrons by an image unit of a photodetector is controlled toacquire an image by FCS. The analyzer described in Document 3 thusprepares a spatial image while scanning the point-like excitation lightand differs in method from the fluorescence correlation spectroscopyanalyzer 1, which performs spatial decomposition using the CCD camera 15having the plurality of pixels arrayed two-dimensionally on thephotodetection surface.

Also, in the case where scanning FCS is used to perform fluorescencecorrelation spectroscopy analysis on the entirety of a measured sample,such as a cell, the image acquisition may need to be made even higher inspeed, depending on the diffusion rate of the sample. However, since inthe case of scanning FCS, an image is acquired while scanning thepoint-like excitation light, the exposure time of one point in a singleimage is extremely short in comparison to that of the above-describedembodiment, with which the excitation light is illuminated over theentirety of the predetermined region R of the measured sample S. Thus,with scanning FCS, the sensitivity of the photodetector becomesinadequate when the image acquisition is made high in speed.

The arrangement of the CCD camera 15 of FIG. 1 shall now be describedwith reference to FIG. 2. FIG. 2 is a plan view showing the CCD camera15 as viewed from the photodetection surface side. However, the transfercontrol unit 152 and the electronic shutter signal outputting unit 154,which are shown in FIG. 1, are omitted from illustration. The CCD camera15 is of a frame transfer type, wherein a photodetection portion 31 andan accumulation portion 36 are provided separately. The plurality ofpixels P are arrayed two-dimensionally along the vertical direction(up/down direction in the figure) and the horizontal direction(left/right direction in the figure) on the surface of the CCD camera15. Here, an example where a total of 120 pixels P are arrayed in twelvestages in the vertical direction shall be described. In each stage, tenpixels are aligned in the horizontal direction.

These pixels P are divided into pixels making up the photodetectionportion 31 and pixels making up the accumulation portion 36. That is, ofall of the pixels P, the 60 pixels contained in the upper half (from thefirst stage to the sixth stage from the top) make up the photodetectionportion 31 and the 60 pixels contained in the lower half (from theseventh stage to the twelfth stage from the top) make up theaccumulation portion 36. The surface of the photodetection portion 31 isthe photodetection surface 32. At each pixel P that makes up thephotodetection portion 31, the incident fluorescence isphotoelectrically converted and the charges generated by thephotoelectric conversion are transferred one stage at a time in thevertical direction. The charges that are transferred in the verticaldirection from the pixels of the lowermost stage of the photodetectionportion 31 are transferred to the pixels of the uppermost stage of theaccumulation portion 36. At each pixel making up the accumulationportion 36, the charges received from the photodetection portion 31 aretransferred one stage at a time in the vertical direction.

Also, a horizontal transfer register 38 is provided adjacent thelowermost stage of the accumulation portion 36. The charges transferredin the vertical direction from the pixels of the lowermost stage of theaccumulation portion 36 are transferred to the horizontal transferregister 38. At the horizontal transfer register 38, the chargesreceived from the accumulation portion 36 are transferred in thehorizontal direction and thereby guided to an output terminal 38 a. Thecharges guided to the output terminal 38 a are output as detectionsignals. A reading circuit 39 is connected to the output terminal 38 aof the horizontal transfer register 38. The detection signals outputfrom the output terminal 38 a of the horizontal transfer register 38 areread by the reading circuit 39.

FIG. 3 is an arrangement diagram showing an example of an optical systemin the fluorescence correlation spectroscopy analyzer 1 of FIG. 1. InFIG. 3, the CCD camera 15 is positioned so that its photodetectionsurface 32 is perpendicular to the optical axis direction (left/rightdirection in the figure) of the fluorescence that is made incidentthereon. The direction perpendicular to the paper surface is thehorizontal direction of the photodetection surface 32 of the CCD camera15, and the up/down direction in the figure is the vertical direction ofthe photodetection surface 32. In the excitation light illuminatingoptical system 21, equipped in the fluorescence correlation spectroscopyanalyzer 1, a laser light source 11, a mirror 121, a cylindrical lens122, a dichroic mirror 131, a galvanomirror 132, a lens 133, and anobjective lens 134 are disposed in that order along the optical pathtoward the measured sample S.

The laser light source 11 outputs laser light (excitation light) forexciting the fluorescent molecules in the measured sample S. The laserlight source 11 is preferably a CW laser light source. As a CW laserlight source, for example, an Ar laser of a wavelength of 488 nm may beused.

The mirror 121 is disposed at a position onto which the excitation lightoutput from the laser light source 11 is made incident. The mirror 121reflects the incident excitation light toward the cylindrical lens 122.

The cylindrical lens 122 is disposed at a position onto which theexcitation light reflected by the mirror 121 is made incident. Thecylindrical lens 122 is an excitation light shaping means that shapesthe incident excitation light. That is, the cylindrical lens 122refracts the incident excitation light in just one direction to shapethe cross-sectional shape in a plane perpendicular to the optical axisof the excitation light beam and emits the shaped excitation light. Arectangular shape (slit-like shape) can be cited as an example of theshape of the shaped excited light. In this case, a rectangularexcitation light is illuminated onto the measured sample S. Also, thecylindrical lens 122 is positioned so that the direction of the longside of the rectangular shape corresponds to the horizontal direction ofthe photodetection surface 32 of the CCD camera 15.

The dichroic mirror 131 is disposed at a position onto which theexcitation light emitted from the cylindrical lens 122 is made incident.The dichroic mirror 131 reflects the excitation light emitted from thecylindrical lens 122 toward the galvanomirror 132. Also, as shall bedescribed later, the dichroic mirror 131 allows the transmission of thefluorescence reflected by the galvanomirror 132 and eliminates theexcitation light that is made incident upon being reflected by themeasured sample S, etc., at that point.

The galvanomirror 132 is disposed at a position onto which theexcitation light reflected by the dichroic mirror 131 is made incident.The galvanomirror 132 reflects the excitation light reflected by thedichroic mirror 131 toward the lens 133. Also, the galvanomirror 132 isa scanning means that scans the excitation light one-dimensionallyacross the measured sample S by being driven by a driver (not shown).When for example, the excitation light is shaped to a rectangular shapeby the cylindrical lens 122, the direction of scanning of the excitationlight by the galvanomirror 132 is set to the direction of the short sideof the rectangular shape. The above-mentioned driver is connected to thedata analyzer 16 (see FIG. 1) and the driver drives the galvanomirror132 based on instructions from the data analyzer 16.

The lens 133 is disposed at a position onto which the excitation lightreflected by the galvanomirror 132 is made incident. The lens 133 guidesthe excitation light reflected by the galvanomirror 132 to the objectivelens 134.

The objective lens 134 is disposed at a position onto which theexcitation light guided by the lens 133 is made incident. The objectivelens 134 illuminates the excitation light, guided and made incident bythe lens 133, onto the measured sample S.

The above-mentioned dichroic mirror 131, the galvanomirror 132, the lens133, and the objective lens 134 make up a fluorescence microscope 13. Inaddition to the dichroic mirror 131, the galvanomirror 132, the lens133, and the objective lens 134, the fluorescence microscope 13 isarranged with a stage 135, a mirror 136, and an ocular lens 137. Thestage 135 is for placing the measured sample S. The mirror 136 isincluded in the fluorescence imaging optical system 22 to be describedlater and is for converting the optical path of the fluorescence that istransmitted through the dichroic mirror 131. The ocular lens 137 isdisposed to enable a measurer to view, as necessary, the conditions ofthe measured sample S illuminated by the excitation light. When theocular lens 137 is needed, a half-mirror is used as the mirror 136 toguide a portion of the fluorescence from the measured sample S to theocular lens 137. Or, the mirror 136 may be disposed so as to be movableand the mirror 136 may be removed from the optical path of thefluorescence when the ocular lens 137 is to be used.

The fluorescence imaging optical system 22, equipped in the fluorescencecorrelation spectroscopy analyzer 1, has the objective lens 134, thelens 133, the galvanomirror 132, the dichroic mirror 131, the mirror136, a lens 141, and a sharp cut filter 142 disposed in that order alongthe optical path from the measured sample S to the CCD camera 15. Thedichroic mirror 131, the galvanomirror 132, the lens 133, and theobjective lens 134 are provided in common to the excitation lightilluminating optical system 21 and the fluorescence imaging opticalsystem 22.

The fluorescence generated at the measured sample S becomes incident onthe objective lens 134, which guides the incident fluorescence to thelens 133. The lens 133 guides the fluorescence, which has been madeincident upon being guided by the objective lens 134, to thegalvanomirror 132. The galvanomirror 132 reflects the fluorescence,which has been made incident upon being guided by the lens 133, to thedichroic mirror 131. The dichroic mirror 131 allows the fluorescence,which has been reflected by the galvanomirror 132, to be transmitted.

The mirror 136 is disposed at a position onto which the fluorescence,transmitted from the dichroic mirror 131 is made incident. The mirror136 reflects the fluorescence, which has been made incident upon beingtransmitted through the dichroic mirror 131, and thereby converts thefluorescence optical path and makes the fluorescence optical path bematched with the image pickup axis of the CCD camera 15.

The lens 141 is disposed at a position onto which the fluorescence,reflected by the mirror 136, is made incident. Lens 141 guides thefluorescence, reflected by the mirror 136, to the CCD camera 15 andimages the fluorescence on the photodetection surface 32 of the CCDcamera 15.

The sharp cut filter 142 is disposed in the optical path between thelens 141 and the CCD camera 15. As the sharp cut filter 142, an opticalfilter, having a property of transmitting the wavelength component ofthe fluorescence generated at the measured sample S and practically nottransmitting the wavelength component of the excitation lightilluminated onto the measured sample S, is used. The sharp cut filter142 thus transmits the fluorescence that is made incident on thephotodetection surface 32 of the CCD camera 15 and at the same timeeliminates the excitation light that tends to be made incident on thephotodetection surface 32 of the CCD camera 15 along the same opticalpath as the fluorescence. This excitation light is that which isreflected by the measured sample S, etc.

With the optical system of FIG. 3, the excitation light is scanned withrespect to the measured sample S by means of the galvanomirror 132.Fluorescence correlation spectroscopy analysis can thereby be performedover a wide range of the measured sample S. Also, by the galvanomirror132 being the scanning means, the excitation light can be scanned withrespect to the measured sample S at an especially high precision.However, if there is not need to scan the excitation light, thegalvanomirror 132 does not have to be provided. An arrangement is alsopossible wherein, in place of using the galvanomirror 132, theexcitation light is scanned with respect to the measured sample S bymovement of the stage 135 of the fluorescence microscope 13.

The galvanomirror 132 is also provided in common to the excitation lightilluminating optical system 21 and the fluorescence imaging opticalsystem 22. Thus, the excitation light illuminated onto the measuredsample S and the fluorescence generated at the measured sample S areboth reflected by the galvanomirror 132. Thus, even if the position ofillumination of the excitation light with respect to the measured sampleS is displaced by the galvanomirror 132, since this displacement iscanceled out when the fluorescence is reflected by the galvanomirror132, the position of incidence of the fluorescence onto thephotodetection surface 32 of the CCD camera 15 will not be displaced.Thus, in the case where fluorescence correlation spectroscopy analysisis performed while scanning the excitation light with respect to themeasured sample S, the patterns of charge transfer and reading controlat the CCD camera 15 do not need to be changed, regardless of theillumination position of the excitation light on measured sample S.Thus, by the fluorescence correlation spectroscopy analyzer 1,fluorescence correlation spectroscopy analysis can be performed readilyon the entirety of the measured sample S.

Also, in the case where a CW laser light source is used as the laserlight source 11, the cost can be made lower in comparison to the casewhere a pulsed light source is used.

FIGS. 4A to 4D are diagrams for describing the flow of fluorescencecorrelation spectroscopy analysis using the fluorescence correlationspectroscopy analyzer 1 shown in FIG. 1. First, by means of theexcitation light illuminating optical system 21 (see FIG. 3), theexcitation light is illuminated onto the measured sample S placed on thestage 135 of the fluorescence microscope 13. Here, by shaping theexcitation light to a rectangular shape by means of the cylindrical lens122 of the excitation light illuminating optical system 21, excitationlight of a rectangular shape is illuminated onto the measured sample S(FIG. 4A). In FIG. 4A, the region surrounded by dashed lines L1 is theregion onto which the excitation light is illuminated.

The fluorescence generated at the measured sample S onto which theexcitation light is illuminated is imaged by the fluorescence imagingoptical system 22 on the photodetection surface 32 of the CCD camera 15.Here, the fluorescence incidence region 32 a is the region of thephotodetection surface 32 of the CCD camera 15 onto which thefluorescence is made incident (FIG. 4B). The fluorescence incidenceregion 32 a has a rectangular shape and the longitudinal directionthereof is matched to the horizontal direction (left/right direction inthe figure) of the photodetection surface 32.

The temporal variations of the fluorescence intensities at therespective pixels in the fluorescence incidence region 32 a are measuredby driving the CCD camera 15 at a high frame rate. By then determiningautocorrelation functions from these temporal variations, measurementdata D can be obtained simultaneously for all of the pixels in thefluorescence incidence region 32 a (FIG. 4C). Here, all of the pixels inthe fluorescence incidence region 32 a are selected as the pixelsbelonging to the analyzed pixel set 33 a. Furthermore, by scanning theexcitation light with respect to the measured sample S by means of thegalvanomirror 132 (see FIG. 3), measurement data D are obtained for theentirety of the measured sample S (FIG. 4D). This scanning direction isorthogonal to the longitudinal direction of the excitation light ofrectangular shape that is illuminated onto the measured sample S.Measurement data D, which are obtained by the FCS method, are, forexample, the relaxation times and the y-intercepts of theautocorrelation functions. Since the relaxation times and y-interceptsreflect the sizes and numbers of the fluorescent molecules in a cell(measured sample S), information concerning at which portions of thecell the molecules are binding to each other or are moving and how thesizes and numbers of the molecules change accordingly at the respectivepositions of the cell are acquired for the entire cell at high speed.

An example of the operations of reading detection signals from the CCDcamera 15 in the fluorescence correlation spectroscopy analyzer 1 shallnow be described with reference to FIG. 5 and FIGS. 6A to 6D. FIG. 5shows the photodetection surface 32 of the CCD camera 15, which isexposed to the fluorescence from the measured sample S. Thephotodetection surface 32 is divided into a first stage 321 to a sixthstage 326 in the vertical direction (up/down direction in the figure),and each of stages 321 to 326 has ten pixels aligned in the horizontaldirection (left/right direction in the figure). The photodetectionsurface 32 thus has a total of 60 pixels arrayed two-dimensionally. Ofthese 60 pixels, the fluorescence is made incident only on the 20 pixelsbelonging to the fifth stage 325 and sixth stage 326. This region ontowhich the fluorescence is made incident is the fluorescence incidenceregion 32 a. Here, the analyzed pixel set 33 a are selected so as to becomprised of the pixels that make up the fluorescence incidence region32 a, that is, the 20 pixels belonging to the fifth stage 325 and sixthstage 326.

FIGS. 6A to 6D show the accumulation portion 36 and the horizontaltransfer register 38 of the CCD camera 15. The charges generated byphotoelectric conversion of the fluorescence at the respective pixels ofthe photodetection surface 32 in FIG. 5 are transferred one stage at atime in the vertical direction toward the accumulation portion 36. FIG.6A shows a state immediately after the charges, generated at therespective pixels belonging to the analyzed pixel set 33 a of thephotodetection surface 32 have been transferred to the accumulationportion 36.

That is, in FIG. 6A, the charges generated at the analyzed pixel set 33a are accumulated in the respective pixels of a first stage 371 and asecond stage 372 of the accumulation portion 36. A circle is marked ineach of the pixels in which charges generated at the pixels belonging tothe analyzed pixel set 33 a are accumulated. Immediately after all ofthe charges generated at the analyzed pixel set 33 a have thus beentransferred to the accumulation portion 36, the electronic shuttersignal is sent to the photodetection surface 32 and all of the chargesgenerated at the pixels of photodetection surface 32 that do not belongto the analyzed pixel set 33 a are swept away.

Furthermore, at the photodetection surface 32, immediately after thecharges have been swept away, the next exposure is carried out, and thecharges generated at the analyzed pixel set 33 a by this exposure aretransferred to the accumulation portion 36. FIG. 6B shows the stateimmediately after the charges, generated at the analyzed pixel set 33 aby this exposure, have been transferred to the accumulation portion 36.At this point, the charges generated at the analyzed pixel set 33 a bythe previous exposure are transferred to a third stage 373 and a fourthstage 374. In FIG. 6B, circles are marked in the pixels in which areaccumulated the charges generated by the previous exposure (shall bereferred to as the “first exposure”) and triangles are marked in thepixels in which are accumulated the charges generated by the presentexposure (shall be referred to as the “second exposure”).

The above operations are repeated, and after the charges generated atthe analyzed pixel set 33 a have been successively accumulated in all ofthe first stage 371 to a sixth stage 376 of the accumulation portion 36as shown in FIG. 6C, these charges are transferred one stage at a timeto the horizontal transfer register 38 and the charges are transferredsuccessively by the horizontal transfer register 38 toward the readingcircuit 39. Exposure of the photodetection surface 32 is carried outduring this operation as well. However, the exposure time must be set tobe no greater than the time required for the horizontal transferregister 38 to transfer all of the charges of a single stage.

In FIG. 6C, the charges generated by the first exposure are accumulatedin a fifth stage 375 and sixth stage 376, the charges generated by thesecond exposure are accumulated in the third stage 373 and fourth stage374, and the charges generated by the third exposure (indicated by thesquares in the figure) are accumulated in the first stage 371 and secondstage 372. Also, FIG. 6D shows the state wherein the charges, generatedin the first exposure at the sixth stage 326 of the photodetectionsurface 32 among the analyzed pixel set 33 a, have been transferred tothe horizontal transfer register 38.

Though in FIG. 6D, charges generated by a fourth exposure are actuallyaccumulated in the first stage 371, illustration thereof is omitted.After transferring the charges of this stage to the reading circuit 39,the horizontal transfer register 38 performs the transfer of the chargesof the next stage. The reading of the detection signals of a singleframe detected by the CCD camera 15 is completed by the above. Thus, inthe reading operations of this example, just the charges generated byphotoelectric conversion at the pixels belonging to the analyzed pixelset 33 a of the photodetection surface 32 are output from the CCD camera15 as the actual detection signals.

In the present example, by electronic shutter outputting unit 154outputting the electronic shutter signal to the photodetection surface32 of the CCD camera 15, the charges generated at the respective pixelsnot belonging to the analyzed pixel set 33 a are swept away. Just thecharges generated at the analyzed pixel set 33 a (the pixels belongingto the fifth stage 325 and sixth stage 326 in FIG. 5) can thus betransferred repeatedly to the accumulation portion. Also, since thetransfer by the horizontal transfer register 38 is carried out evenduring exposure of the photodetection surface 32, data can be acquiredat a high repetition rate with the time taken for the horizontaltransfer register 38 to horizontally transfer the charges generated atthe analyzed pixel set 33 a as the minimum.

In particular, with the present example, since the analyzed pixel set 33a is set so as to include the pixels of the sixth stage 326 of thephotodetection surface 32, which is adjacent to the accumulation portion36, the fluorescence information of a single frame can be readsuccessively without gaps from the CCD camera 15 at time intervals takenfor transfer of the charges of the few lines (two lines in the presentexample) in the vertical direction that make up the analyzed pixel set33 a. Thus, with the fluorescence correlation spectroscopy analyzer 1,the detection signals can be read at an especially high speed.

FIG. 7 shows timing charts that illustrate the operation timing of theCCD camera 15 in the reading operation described using FIG. 5 and FIGS.6A to 6D. The respective charts in FIG. 7 illustrate, from the top, theelectronic shutter timing, the exposure timing, the charge transfertiming, and the control timing.

The electronic shutter timing is the timing at which the electronicshutter is shut, that is, the timing at which the electronic shuttersignal outputting unit 154 outputs the electronic shutter signal to thephotodetection surface 32 (see FIG. 5). The electronic shutter is shutimmediately prior to the start of exposure. The exposure timingexpresses the timing at which the respective pixels of thephotodetection surface 32 are exposed. The exposure time is set, forexample, to 10 μs. The charge transfer timing expresses the timing fortransfer of the charges, generated at the analyzed pixel set 33 a of thephotodetection surface 32, to the accumulation portion 36 in thevertical direction. The charge transfer is started immediately after theend of exposure. The control timing is the timing of control from thestart of exposure to the start of the next exposure.

An example of the operations of the data analyzer 16 of FIG. 1 shall nowbe described using FIG. 8 and FIG. 9. FIG. 8 is a graph showing anexample of the variation in time of the fluorescence intensity detectedby the CCD camera 15. The ordinate of the graph expresses thefluorescence intensity and the abscissa indicates the time. Both theordinate and abscissa are of arbitrary scales. FIG. 9 is a graph showingan autocorrelation function G(τ) determined based on the graph of FIG.8. The ordinate of the graph expresses G(τ) and the abscissa indicatesthe time τ. Both the ordinate and the abscissa are of arbitrary scales.This autocorrelation function G(τ) is defined by the following equationwith t being the time and I(t) being the fluorescence intensity at timet:G(τ)=<I(t)·I(t+τ)>/<I(t)>²In the above, <I(t)> indicates the average value of I(t).

Based on the detection signals detected by the CCD camera 15, the dataanalyzer 16 determines the autocorrelation function G(τ) for each pixelbelonging to the analyzed pixel set 33 a of the photodetection surface32 and furthermore computes the relaxation time τ₀ and the y-interceptG(0) from each autocorrelation function G(τ). Since the relaxation timeτ₀ and the y-intercept G(0) are functions of the size and number,respectively, of fluorescent molecules, the size and number offluorescent molecules can be determined from the relaxation time τ₀ andthe y-intercept G(0). Here, the relaxation time τ₀ is defined as the τfor which G(τ)=(½)G(0). With the data analyzer 16, informationconcerning at which portions of a cell (measured sample S) molecules arebinding with each other or are moving and how the sizes and numbers ofmolecules are changing accordingly can be acquired for the entire cellin a short time based on the autocorrelation functions G(τ).

FIGS. 10A to 10E are diagrams for describing a modification example ofthe fluorescence correlation spectroscopy analyzer 1 of FIG. 1. In thismodification example, the method of control of the CCD camera 15 by thetransfer control unit 152 differs from that of the fluorescencecorrelation spectroscopy analyzer 1 of FIG. 1. Besides this, thearrangement is the same as that of the fluorescence correlationspectroscopy analyzer 1 of FIG. 1.

FIG. 10A shows the state after the charges that have been generated inthe respective pixels in the photodetection surface 32 of the CCD camera15 have been transferred to the corresponding pixels of the accumulationportion 36. With the present modification example, unlike the caseillustrated in FIG. 6A, an electronic shutter signal is not output bythe electronic shutter signal outputting unit 154 to the pixels notbelonging to the analyzed pixel set 33 a of the photodetection surface32. The charges accumulated in the pixels belonging to the first stage371, the second stage 372, the fifth stage 375, and the sixth stage 376,which correspond to the pixels not belonging to the analyzed pixel set33 a, are thus not necessarily 0. In the figure, the pixels in which thecharges generated at the pixels belonging to the analyzed pixel set 33 aare accumulated are indicated by circles, and the pixels in which thecharges generated at pixels not belonging to the analyzed pixel set 33 aare indicated by single slanted lines.

From the state of FIG. 10A, a transfer signal is input from the transfercontrol unit 152 into each pixel of the accumulation portion 36. Thecharges of the respective pixels of the accumulation portion 36 aretransferred one stage at a time in the direction of the horizontaltransfer register 38. The charges accumulated in the pixels of the sixthstage 376 of the accumulation portion 36 are thus transferred to thehorizontal transfer register 38 as shown in FIG. 10B.

When the transfer signals are input into the accumulation portion 36from the transfer control unit 152 again, the charges that wereaccumulated in the pixels of the fifth stage 375 in FIG. 10A are alsotransferred to the horizontal transfer register 38. Thus, in FIG. 10C,the charges that were accumulated in the pixels of the fifth stage 375and sixth stage 376 in FIG. 10A are overlapped in the horizontaltransfer register 38. In FIG. 10C, double slanted lines are indicated inthe respective regions of the horizontal transfer register 38 toindicate that the charges of two stages are overlapped.

From the state of FIG. 10C, the transfer signal is input from thetransfer control unit 152 to horizontal transfer register 38 and thecharges accumulated in the horizontal transfer register 38 are swept outsuccessively (FIG. 10D). Here, the charges that were accumulated in thepixels of the fourth stage 374 in FIG. 10A are not transferred to thehorizontal transfer register 38 from the state of FIG. 10C since thepixels of the fourth stage 374 in FIG. 10A correspond to the pixelsbelonging to the analyzed pixel set 33 a and thus accumulate the chargesto be read as detection signals. After all of the charges accumulated inthe horizontal transfer register 38 have thus been swept out, thetransfer signals are input from the transfer control unit 152 to theaccumulation portion 36 and the charges that were accumulated in thepixels of the fourth stage 374 in FIG. 10A are transferred to thehorizontal transfer register 38 (FIG. 10E). Thereafter, the transfersignal is input from the transfer control unit 152 to the horizontaltransfer register 38 and the charges that were accumulated in the pixelsof the fourth stage 374 in FIG. 10A are output as detection signals tothe reading circuit 39.

FIGS. 11A to 11G are diagrams for describing another modificationexample of the fluorescence correlation spectroscopy analyzer 1 ofFIG. 1. In this modification example, the method of control of the CCDcamera 15 by the transfer control unit 152 differs from that of thefluorescence correlation spectroscopy analyzer 1 of FIG. 1. Also, theanalyzed pixel set in photodetection surface 32 of the CCD camera 15differs from the analyzed pixel set 33 a. The analyzed pixel set iscomprised of the fourth to seventh pixels from the left in the thirdstage 323 and fourth stage 324 (see FIG. 5) of the photodetectionsurface 32 (a total of eight pixels). Besides the above, the arrangementis the same as that of the fluorescence correlation spectroscopyanalyzer 1 of FIG. 1.

FIG. 11A shows the state after the charges that have been generated inthe respective pixels in the photodetection surface 32 of the CCD camera15 have been transferred to the corresponding pixels of the accumulationportion 36. As with the example of FIG. 10A, with the presentmodification example, an electronic shutter signal is not output by theelectronic shutter signal outputting unit 152 to the pixels notbelonging to the analyzed pixel set of the photodetection surface 32. Inthe figure, the pixels in which the charges generated at the pixelsbelonging to the analyzed pixel set are accumulated are indicated bycircles, and the pixels in which the charges generated at pixels notbelonging to the analyzed pixel set are indicated by single slantedlines.

From the state of FIG. 11A, the transfer signal is input from thetransfer control unit 152 into each pixel of the accumulation portion36. The charges of the respective pixels of the accumulation portion 36are transferred one stage at a time in the direction of the horizontaltransfer register 38. The charges accumulated in the pixels of the sixthstage 376 of the accumulation portion 36 are thus transferred to thehorizontal transfer register 38 as shown in FIG. 11B. When the transfersignals are input into the accumulation portion 36 from the transfercontrol unit 152 again, the charges that were accumulated in the pixelsof the fifth stage 375 in FIG. 11A are also transferred to thehorizontal transfer register 38. Thus, in FIG. 11C, the charges thatwere accumulated in the pixels of the fifth stage 375 and sixth stage376 in FIG. 11A are overlapped in the horizontal transfer register 38.In FIG. 11C, double slanted lines are indicated in the respectiveregions of the horizontal transfer register 38 to indicate that thecharges of two stages are overlapped.

From the state of FIG. 11C, the transfer signal is input from thetransfer control unit 152 to the horizontal transfer register 38 and thecharges accumulated in the horizontal transfer register 38 are swept outsuccessively. When as shown in FIG. 11D, the charges accumulated in thehorizontal transfer register 38 are swept out successively and thecharges of the charge accumulating elements of the horizontal transferregister 38 corresponding to the pixels of the fourth stage 374 thatwere provided with circles in FIG. 11A are swept out and these chargeaccumulating elements become able to accept new charges, the transfersignals are output from the transfer control unit 152 to theaccumulation portion 36. Thus, as shown in FIG. 11E, the charges thatwere accumulated in the pixels of the fourth stage 374 that wereprovided with circles in FIG. 11A are transferred to the horizontaltransfer register 38 without becoming overlapped with other charges. Atthe charge accumulating elements at the reading circuit side of thecharge accumulating elements that receive the charges, which wereaccumulated in the pixels of the fourth stage 374 that were providedwith circles in FIG. 11A, the charges that were accumulated in thepixels of the fourth stage 374, fifth stage 375, and sixth stage 376 inFIG. 11A are accumulated overlappingly.

At the point at which the state of FIG. 11E is, attained, the transfersignal is output from the transfer control unit 152 to the horizontaltransfer register 38 and the charges accumulated in the horizontaltransfer register 38 are swept out successively. When as shown in FIG.11F, the charges accumulated in the horizontal transfer register 38 areswept out successively and the charges of the charge accumulatingelements of the horizontal transfer register 38 corresponding to thepixels of the third stage 373 that were provided with circles in FIG.11A are swept out and these charge accumulating elements become able toaccept new charges, the transfer signals are output from the transfercontrol unit 152 to the accumulation portion 36. Thus, as shown in FIG.11G, the charges that were accumulated in the pixels of the third stage373 that were provided with circles in FIG. 11A are transferred to thehorizontal transfer register 38 without becoming overlapped with othercharges.

FIGS. 12A to 12G are diagrams for describing another modificationexample of the fluorescence correlation spectroscopy analyzer 1 ofFIG. 1. This modification example differs from the fluorescencecorrelation spectroscopy analyzer 1 of FIG. 1, which uses a frametransfer type CCD camera 15, in that an interline type CCD image pickupelement is used.

The CCD image pickup element of this modification example is providedwith a photodetection surface 42 and a horizontal transfer register 48(second charge accumulating elements). Photodetection surface 42 isdivided into a first stage 421 to a sixth stage 426 in the verticaldirection and in each of stages 421 to 426, ten photodiodes (pixels) 44a are aligned in the horizontal direction. Adjacently to the right sidein the figure of each pixel is disposed a vertical transfer CCD (firstcharge accumulating element) 44 b. The analyzed pixel set of thismodification example is comprised of the fourth to seventh pixels fromthe left of a third stage 423 and a fourth stage 324. Here, it shall bedeemed that fluorescence is incident on all of the pixels belonging tothe analyzed pixel set. Also, the horizontal transfer register 48 isprovided adjacent the sixth stage 426 of the photodetection surface 42.

FIG. 12A schematically illustrates a state wherein the fluorescence fromthe measured sample S is made incident on the photodetection surface 42.In FIG. 12A, symbols “A” are provided, respectively, in the pixels inwhich the charges generated at the pixels belonging to analyzed pixelset 43 a are accumulated. When in the state of FIG. 12A, the transferpulse signals are output from the transfer control unit 152 to thephotodetection surface 42, the charges generated by photoelectricconversion at the respective pixels in the analyzed pixel set are outputto the vertical transfer CCDs 44 b and the state of FIG. 12B isattained. Since the respective pixels are put in states enablingexposure once the charges resulting from photoelectric conversion havebeen output, fluorescence can be detected at the same portions as thosein FIG. 12A as shown in FIG. 12C. In order to distinguish from thecharges detected in FIG. 12A, symbols “B” are provided in the pixels inwhich are accumulated the charges generated by the photoelectricconversion of the fluorescence made incident anew in FIG. 12C.

While fluorescence is thus being detected anew, the charges (“A”) outputto the vertical transfer CCDs 44 b in FIG. 12B are transferred in thedirection of the horizontal transfer register 48. At the point at whichthe charges have been transferred from the vertical transfer CCDs 44 bcorresponding to the regions provided with the symbols “B” and thereceiving of new charges are enabled, the transfer pulse signals areoutput from the transfer control unit 152 to the photodetection surface42 and the state shown in FIG. 12D is entered.

Since the respective pixels are put in states enabling exposure once thecharges resulting from photoelectric conversion have been output, asshown in FIG. 12E, fluorescence can be detected at the same portions asthose in FIGS. 12A and 12C. In order to distinguish from the chargesdetected in FIGS. 12A and 12C, symbols “C” are provided in the pixels inwhich are accumulated the charges generated by the photoelectricconversion of the fluorescence made incident anew in FIG. 12E. Whilefluorescence is thus being detected anew, the charges (“A” and “B”)output to the vertical transfer CCDs 44 b are transferred in thedirection of the horizontal transfer register 48 and the charges (“A”)resulting from the photoelectric conversion at the fourth stage 424 ofFIG. 12A are transferred to the horizontal transfer register 48.

The charges (“A”) transferred to the horizontal transfer register 48 aretransferred in the direction of reading circuit 49 and the state of FIG.12F is entered. When as shown in FIG. 12F, the charges accumulated inthe horizontal transfer register 48 have been swept out successively andthe charges (“A”) of the fourth stage 424 in FIG. 12A have been sweptout and the corresponding charge accumulating elements become able toaccept new charges, the transfer signals are output from the transfercontrol unit 152 to the photodetection surface 42. Thus, as shown inFIG. 12G, the charges resulting from the photoelectric conversion at thepixels of the third stage 423 provided with the symbols “A” in FIG. 12Aare transferred to the horizontal transfer register 48 without becomingoverlapped with other charges.

The effects of the modification examples described using FIGS. 10A to10E, FIGS. 11A to 11G, and FIGS. 12A to 12G shall now be described withreference to FIGS. 13A to 13D. FIG. 13A shows timing charts of anarrangement of a comparative example wherein the charges generated atall pixels are output as detection signals, FIG. 13B shows timing chartsfor the modification example described using FIGS. 10A to 10E, FIG. 13Cshows timing charts for the modification example described using FIGS.11A to 11G, and FIG. 13D shows timing charts for the modificationexample described using FIGS. 12A to 12G. In the respective timingcharts of FIGS. 13A to 13D, the vertical synchronization is illustratedin the upper stage and the horizontal synchronization is illustrated inthe lower stage. Also, in each of the lower stages, a circle oralphabetical character indicates the transfer of charges generated atpixels belonging to the analyzed pixel set and a slanted line indicatesthe transfer of charges generated at pixels not belonging to theanalyzed pixel set.

With the comparative example shown in FIG. 13A, since charges resultingfrom the photoelectric conversion by the pixels of each stage are readone stage at a time, reading in the horizontal direction must be carriedout for six stages. Meanwhile, with the example shown in FIG. 13B (themodification example described using FIGS. 10A to 10E), since thecharges resulting from the photoelectric conversion by the pixels notbelonging to the analyzed pixel set are overlapped, even with the samehorizontal direction transfer rate, the reading time of the charges of asingle frame can be shortened. The detection signals can thus be read ata high speed.

With the example shown in FIG. 13C (the modification example describedusing FIGS. 11A to 11G), although the pixels belonging to the thirdstage 323 and fourth stage 324 include both pixels belonging to theanalyzed pixel set and pixels not belonging to the analyzed pixel set,even if a portion of the pixels are pixels belonging to the analyzedpixel set, the charges, resulting from photoelectric conversion by thepixels of the same stage as those pixels that do not belong to theanalyzed pixel set, are read overlappingly. The reading time of thecharges of a single frame can thus be shortened further. The detectionsignals can thus be read out at an even higher speed.

With the example shown in FIG. 13D (the modification example describedusing FIGS. 12A to 12G), since an interline type CCD image pickupelement is used, the charges of the pixels belonging to the analyzedpixel set can be read without being influenced by the reading of thecharges of the pixels not belonging to the analyzed pixel set. Thedetection signals can thus be read out at high speed. Also, sincereading and exposure can be performed at the same time, the output datacan be handled as a two-dimensional image.

The operation timings of the respective CCDs during the operationsdescribed using FIGS. 10A to 10E, FIGS. 11A to 11G, and FIGS. 12A to 12Gshall now be described using FIGS. 14A, 14B, FIGS. 15A, and 15B. FIG.14A shows timing charts for the case of performing the operations,described using FIGS. 10A to 10E or FIGS. 11A to 11G, using a frametransfer type CCD image pickup element. FIG. 14B shows timing charts forthe case of performing the operations, described using FIGS. 10A to 10Eor FIGS. 11A to 11G, using an interline type CCD image pickup element.

In FIGS. 14A and 14B, PIV indicates image area (photodetection portion)shift pulse signals of a frame transfer type CCD image pickup element,PSV indicates memory area (accumulation portion) shift pulse signals ofthe frame transfer type CCD image pickup element, PH indicateshorizontal CCD shift pulse signals, SG indicates pulse signals fortransfer from photodiodes to vertical transfer CCDs, PV indicatesvertical shift pulse signals, and VV indicates vertical effectivesignals. Here, it shall be deemed that the frame transfer type CCD imagepickup element has an image area of 10×6 pixels and a memory area of10×6 pixels. Comparison of the respective vertical effective signals ofFIGS. 14A and 14B shows that in cases of performing the operationsdescribed in FIGS. 10A to 10E or FIGS. 11A to 11G, reading atsubstantially the same speed is enabled by using either of the frametransfer type CCD image pickup element and the interline type CCD imagepickup element.

FIG. 15A shows timing charts for the case of performing the operations,described using FIGS. 12A to 12G, using an interline type CCD imagepickup element. FIG. 15B shows timing charts for the case of performingthe operations, described using FIGS. 12A to 12G, using a frame transfertype CCD image pickup element. The symbols used in FIGS. 15A and 15B arethe same as the symbols used in FIGS. 14A and 14B. Comparison of therespective vertical effective signals of FIGS. 15A and 15B shows thatwhen the operations described in FIGS. 12A to 12G are performed, thespeed can be improved significantly when the interline type CCD imagepickup element is used. This is because while the necessary areas can beadded onto the unnecessary areas as they are with an interline CCD imagepickup element, the same operation cannot be performed with a frametransfer type CCD image pickup element.

The present invention's fluorescence correlation spectroscopy analyzeris not limited to the above-described embodiments and variousmodifications are possible. For example, with the above-describedembodiments, examples were described wherein the analyzed pixel set isselected so that its region matches the fluorescence incidence region.However, the analyzed pixel set may instead be selected so that aportion of the region thereof contains the fluorescence incidenceregion. Or, the analyzed pixel set may be selected so that the regionthereof is contained in the fluorescence incidence region. Or, theanalyzed pixel set may be selected so that a portion of the regionthereof contains a portion of the fluorescence incidence region.

Other examples of the operations of reading detection signals from theCCD camera 15 in the fluorescence correlation spectroscopy analyzer 1shall now be described with reference to FIGS. 16A to 16L and FIGS. 17Ato 17K (see FIGS. 6A to 6D).

A method of reading charges in a case of using a frame transfer type CCDas an image pickup unit shall now be described using FIGS. 16A to 16F.

Image pickup unit 95 is of a frame transfer type having a separatephotodetection portion (photodetection surface) 95 a and an accumulationportion 95 b. A plurality of pixels P are arrayed two-dimensionallyalong the vertical direction (up/down direction in the figure) and thehorizontal direction (left/right direction in the figure) in imagepickup unit 95. Here, an example where a total of 120 pixels P arearrayed in twelve stages in the vertical direction shall be described.In each stage, ten pixels are aligned in the horizontal direction.

These pixels P are divided into pixels making up the photodetectionportion 95 a and pixels making up the accumulation portion 95 b. Thatis, of all of the pixels P, the 60 pixels contained in the upper half(from the first stage to sixth stage from the top) make up thephotodetection portion and the 60 pixels contained in the lower half(from the seventh stage to twelfth stage from the top) make up theaccumulation portion. At each pixel P that makes up the photodetectionportion 95 a, the incident fluorescence is photoelectrically convertedand the charges generated by the photoelectric conversion aretransferred one stage at a time in the vertical direction. The chargesthat are transferred in the vertical direction from the pixels of thelowermost stage (sixth stage 956) of the photodetection portion 95 a aretransferred to the pixels of the uppermost stage (first stage 957) ofthe accumulation portion 95 b. At each pixel making up the accumulationportion 95 b, the charges received from the photodetection portion 95 aare transferred one stage at a time in the vertical direction.

Also, a horizontal transfer register 96 is provided adjacent thelowermost stage (sixth stage 962) of the accumulation portion 95 b. Thecharges transferred in the vertical direction from the pixels of thelowermost stage (sixth stage 962) of the accumulation portion 95 b aretransferred to the horizontal transfer register 96. At the horizontaltransfer register 96, the charges received from the accumulation portion95 b are transferred in the horizontal direction and output as detectionsignals.

FIG. 16A schematically illustrates a state wherein fluorescence is madeincident on-the photodetection portion 95 a and the respective pixels ofphotodetection portions 95 a are receiving light. In FIG. 16A, it shallbe deemed that the fluorescence is made incident on the region providedwith the symbols “A”. FIG. 16B shows the state immediately after thecharges, generated at the respective pixels belonging to detectionportion 95 a, have been transferred to the accumulation portion 95 b.That is, the charges, which were generated in accordance with theincidence of fluorescence in FIG. 16A, are accumulated in the respectivepixels of a first stage 957 and a second stage 958 of the accumulationportion 95 b, as shown in FIG. 16B. Immediately after all of the chargesgenerated in accordance with the incidence of fluorescence have thusbeen transferred to the accumulation portion 95 b, an electronic shuttersignal is sent to the photodetection portion 95 a and all of the chargesgenerated at the pixels of the photodetection portion 95 a onto whichthe fluorescence is not made incident are swept away (see FIG. 16C).

Furthermore, at the photodetection portion 95 a, immediately after thecharges have been swept away, the next exposure is carried out. In FIG.16D, it shall be deemed that the fluorescence is made incident on theregion provided with the symbols “B”. The charges generated at thephotodetection portion 95 a by this exposure are transferred to theaccumulation portion 95 b. FIG. 16E shows the state immediately afterthe charges generated in accordance with the incidence of fluorescenceby this exposure have been transferred to the accumulation portion 95 b.At this point, the charges generated at the photodetection portion 95 aby the previous exposure are transferred to a third stage 959 and afourth stage 960.

After the above operations have been repeated and the charges generatedin accordance with the incidence of fluorescence have been successivelyaccumulated in all of the first stage 957 to the sixth stage 962 of theaccumulation portion 95 b, these charges are transferred one stage at atime to the horizontal transfer register 96 and the charges aretransferred successively by the horizontal transfer register 96 toward areading circuit. Exposure of the photodetection surface 95 a is carriedout during this operation as well. However, the exposure time must beset to be no greater than the time required for the horizontal transferregister 96 to transfer all of the charges of a single stage. In FIG.16F, the charges generated by the first- exposure are accumulated in afifth stage 961 and sixth stage 962, the charges generated by the secondexposure are accumulated in the third stage 959 and fourth stage 960,and the charges generated by the third exposure (indicated by thesymbols “C” in the figure) are accumulated in the first stage 957 andsecond stage 958. After transferring all of the charges of the firststage (lowermost stage) to the reading circuit, the horizontal transferregister 96 performs the transfer of the charges of the next stage.Thus, in the reading operations of this example, just the chargesgenerated in accordance with the incidence of fluorescence are output asthe actual detection signals.

In the present example, by a control unit (electronic shutter signaloutputting means) outputting the electronic shutter signal, the chargesgenerated at the respective pixels onto which the fluorescence is notmade incident are swept away. Just the charges generated in accordancewith the incidence of fluorescence can thus be transferred repeatedly tothe accumulation portion. Also, since the transfer by the horizontaltransfer register 96 is carried out even during exposure of thephotodetection portion 95 a, data can be acquired at a high repetitionrate with the time taken for the horizontal transfer register 96 tohorizontally transfer the charges generated in accordance with theincidence of fluorescence as the minimum. In particular, with thepresent example, since the region onto which the fluorescence is madeincident is set so as to include the pixels of the sixth stage 956 ofthe photodetection portion 95 a, which is adjacent to the accumulationportion 95 b, the information of the analyzed pixel set (predeterminedregion) can be read successively without gaps at time intervals takenfor transfer of the charges of the few lines (two lines in the presentexample) in the vertical direction that make up the region onto whichthe fluorescence is made incident. The detection signals can thus beread at an especially high speed.

After the state of FIG. 16F, exposure and reading are carried out in themanner described next. The exposure and reading shall now be describedwith reference to FIGS. 16G to 16L. When further exposure is performedfrom the state of FIG. 16F, the state of FIG. 16G is entered. Here, allof the pixels of the accumulation portion 95 b are filled with thecharges that had been transferred. When vertical transfer for a singleline is performed from the state of FIG. 16G, the state of FIG. 16H isentered. When vertical transfer for a single line is performed further,the state of FIG. 16I is entered. In the state shown in FIG. 16I, thecharges accumulated in the first exposure (portions in the FIG. providedwith the symbols “A”) are stored in an overlapping manner in thehorizontal transfer register 96 (indicated in the figure by the symbols“AA”). When the electronic shutter signal is output at this point, thecharges of the pixels belonging to the photodetection portion 95 a areswept away again (see FIG. 16J).

By successively reading the horizontal transfer register 96 at thispoint, an image can be acquired with the definition in the horizontaldirection being maintained (since the charges are overlapped in thevertical direction). Furthermore, during the period of reading of thehorizontal transfer register 96, the next exposure is performed (seeFIG. 16K; the symbols “e” in the figure indicate a state duringexposure). When the reading of the horizontal transfer register 96 iscompleted, the new exposure is also completed (see FIG. 16L; the symbols“E” in the figure indicate the state in which the exposure iscompleted). The state illustrated in FIG. 16L is equivalent to the stateillustrated in FIG. 16G, and thus by repeating the exposure and readingdescribed with reference to FIGS. 16H to 16L, images can be outputcontinuously without unnecessarily dropping the repetition rate of imageoutput.

Yet another example of exposure and reading shall now be described withreference to FIGS. 17A to 17K. With FIGS. 16A to 16L, an example whereoverlapping in the vertical direction is performed at the horizontalreading out stage according to the analyzed pixel set was described.With FIGS. 17A to 17K, a case where overlapping in the verticaldirection is not performed shall be described. In FIGS. 17A to 17C, thesame exposure and transfer as those described with reference to FIGS.16A to 16C are performed. In the case of a frame transfer type CCD, therespective driving in the vertical direction of the photodetectionportion 95 a and accumulation portion 95 b can be performedindependently of each other. Thus, from the state shown in FIG. 17C,transfer in the vertical direction is performed at the accumulationportion 95 b while performing exposure at the photodetection portion 95a (indicated by the symbols “b” in the figure). When vertical transferof two lines have been performed at the accumulation portion 95 b, theexposure at the photodetection portion 95 a is completed (see FIG. 17E).Driving is performed so that a gap of two lines is formed as shown inFIG. 17E because two lines are used as the analyzed pixel set. This gapis thus set based on an appropriate value that is derived from thenumber of lines of the accumulation portion and the vertical unit of thepixel set.

From the state of FIG. 17E, vertical transfer is performed at bothphotodetection portion 95 a and accumulation portion 95 b and the stateof FIG. 17F is entered. The electronic shutter signal is output at thestate shown in FIG. 17F to sweep away the charges accumulated in thephotodetection portion 95 a (see FIG. 17G). When from the state of FIG.17G, further vertical transfer by one line is performed, the first lineof charges, indicated by the symbols “A”, is transferred to thehorizontal transfer register 96, as shown in FIG. 17H. Then as shown inFIG. 17I, exposure is performed at the photodetection portion 95 a whilereading the horizontal transfer register 96 (the symbols “c” in thefigure indicate that exposure is in progress). When the reading of the“A” charges of the first line is completed, further vertical transfer isperformed just at the accumulation portion 95 b to transfer the “A”charges of the next line to the horizontal transfer register 96 (seeFIG. 17J). When the reading of the horizontal transfer register 96 isthen completed, the exposure at the photodetection portion 95 a is alsocompleted and the state shown in FIG. 17K is entered. The stateillustrated in FIG. 17K is equivalent to the state illustrated in FIG.17E, and thus by repeating the exposure and reading described withreference to FIGS. 17F to 17K, images can be output continuously withoutunnecessarily dropping the repetition rate of image output.

INDUSTRIAL APPLICABILITY

The present invention's fluorescence correlation spectroscopy analyzercan be used as a fluorescence correlation spectroscopy analyzer used forthe analysis of protein binding processes and for drug screening, etc.In particular, with the present invention, a fluorescence correlationspectroscopy analyzer, which can perform fluorescence correlationspectroscopy analysis on multiple points of a measured samplesimultaneously and at high speed, is realized.

1. An image pickup device comprising: a photodetection surface, providedwith a plurality of pixels that are arrayed two-dimensionally along afirst direction and a second direction that intersect mutually, andhaving a first pixel set, comprising a portion of pixels selected fromamong the plurality of pixels in accordance with the light incidenceregion, and a second pixel set, comprising pixels not belonging to thefirst pixel set; a horizontal transfer register, receiving andaccumulating the charges that are transferred in the first directionfrom the pixels and transferring the accumulated charges in the seconddirection; and a transfer control means, outputting, to the respectivepixels and the horizontal transfer register, transfer signals fortransferring charges; and wherein the transfer control means outputs thetransfer signals so that the charges generated at the pixels belongingto the second pixel set are overlapped in the first direction andaccumulated in the horizontal transfer register and thereaftertransferred in the second direction, while the charges generated at thepixels belonging to the first pixel set are accumulated in the firstdirection and transferred in the second direction one stage at a time.2. The image pickup device according to claim 1, wherein the transfercontrol means outputs the transfer signals to the pixels belonging tothe first pixel set to make the charges generated at the pixelsbelonging to the first pixel set be transferred in the first direction,and in the case where one stage of pixels aligned in the seconddirection includes a pixel belonging to the first pixel set, outputs thetransfer signals to the horizontal transfer register at the stage priorto the transfer of the charges generated at the one stage of pixels tothe horizontal transfer register.
 3. The image pickup device accordingto claim 1, wherein, in the case where one stage of pixels aligned inthe second direction includes a pixel belonging to the first pixel setand a pixel belonging to the second pixel set, the transfer controlmeans outputs the transfer signals to the pixels of the one stage andthereby makes the charges be transferred to the horizontal transferregister when the elements of the horizontal transfer register, whichcorrespond to the pixels belonging to the first pixel set of the onestage, have charges swept out therefrom and are enabled to receive newcharges.
 4. The image pickup device according to claim 1, furthercomprising an electronic shutter signal outputting means, which outputs,to the photodetection surface, an electronic shutter signal for sweepingaway the charges generated by the pixels belonging to the second pixelset.
 5. An image pickup device comprising: a photodetection surface,provided with a plurality of pixels that are arrayed two-dimensionallyalong a first direction and a second direction that intersect mutually,and having a first pixel set, comprising a portion of pixels selectedfrom among the plurality of pixels in accordance with the lightincidence region, and a second pixel set, comprising pixels notbelonging to the first pixel set; first charge accumulating elements,accumulating charges generated at the respective pixels and transferringthe accumulated charges in the first direction; second chargeaccumulating elements, receiving and accumulating charges transferred inthe first direction from the first charge accumulating elements andtransferring the accumulated charges in the second direction; and atransfer control means, outputting, to the first charge accumulatingelements and the second charge accumulating elements, transfer signalsfor transfer of charges; and wherein, in the case where one stage ofpixels aligned in the second direction includes a pixel belonging to thefirst pixel set and a pixel belonging to the second pixel set, thetransfer control means outputs the transfer signals to the first chargeaccumulating elements corresponding to the pixels of the one stage andthereby makes the charges be transferred to the second chargeaccumulating elements when the second charge accumulating elements,which correspond to the pixels belonging to the first pixel set of theone stage, have charges swept out therefrom and are enabled to receivenew charges.
 6. The image pickup device according to claim 5, furthercomprising an electronic shutter signal outputting means, which outputs,to the photodetection surface, an electronic shutter signal for sweepingaway the charges generated by the pixels belonging to the second pixelset.